London may have had the Sky Ride, but Philadelphia went one step better – or, at least, nakeder – as hundreds of nude cyclists rode through the city on Sunday.

The throngs of naked and partially-naked cyclists took to the streets for the second annual Philly Naked Bike Ride in an effort to promote bicycling awareness and cleaner air. And certainly, it’s hard not to be aware of bicycling when hundreds of naked cyclists are bearing down on you.

Some of the riders went completely naked, while others covered up slightly with underwear, swimming costumes or elaborate body paint. The cyclists rode over a pre-planned route of several miles through the city at dusk on Sunday evening.

Many of the riders covered their bodies in elaborate body paint

This was the second year that the Philly Naked Bike Ride took place, and similar events have taken place in over 70 other cities around the world since 2004.